18.5mm width, 7.7mm thick + 3.7mm for the flange on the back (see photo on mfgr page, https://niteize.com/ziplittm-led-zipper-pull ). Height is 21.1mm because of the little tab where the (non-removable) pull cord goes. Weight is around 2.5-3g. You could file that tab off if you wanted it smaller, then drill a small hole in the rear flange and run some paracord inner strand or dyneema thread through the hole, if you still wanted a lanyard attachment. Without filing the tab, it fits ok “edgewise” into an NDUR match safe (20mm ID), which seems ok because the space around the light is still usable for matches, tinder tabs, etc.

The output is about 1 lumen in a wide flood pattern, so it’s like using your phone screen to see your way around. We’ve all done that, it’s not super bright, but it works. It is definitely a (minimal) functional light and not just a location marker. I calculate (but haven’t yet tested) that the little CR927 lithium cell inside should be able to run the light for several hours at that level. You can remove the “pill” (16.5mm dia, 6.1mm thick, plus flange) from the outer housing if you want the light smaller still, but you may give up waterproofness and protection of the (0203 sized surface mount) LED. A layer of clear nail polish (what McGizmo used to call “poor man’s conformal coating”) might help with that. I don’t have a precise scale nearby but the pill weight (incl. battery) must be under 2g.

Unfortunately the CR927 battery is a bit hard to find, especially from recognizable brands. Exell is one brand that is supposedly legit, and there is a decent ebay offer here (search for “Exell CR927”). I will probably order some of those. It seems to me that with a little careful sanding of the battery compartment, you could squeeze in the more common CR1025 and get a little bit more runtime in the process. But I haven’t yet tried this.

I think if you want a zipper pull light or small light for practical use, the venerable Photon II is a better bet. There are also “dog collar” lights that can work as zipper pulls, that use a CR2032 cell that has around 10x the capacity of the CR927. But this thing is nice if you have extreme space constraints. It is the smallest light that I actually know where to buy.

Suggestions for Nite-ize if they see this:

• Enlarge battery compartment to use CR1025 cell. I think this is doable while keeping external size the same.
• Change black zipper pull cord to a more visible color like orange
• Put some GITD paint around the led if that doesn’t increase cost too much. I might try that as a mod for my own units.
• Add a bigger version to the product line, using a 2032 cell and maybe 2 or 3 of those tiny LEDs.